1. Field of the Invention
The present invention relates to a recorder, and more particularly to a recorder for recording on a record medium by recording liquid.
2. Related Background Art
In a conventional recorder, a carriage on which a record element is mounted scans over a record medium to record data. A flexible ink supply tube is connected to the record element to supply ink to the record element as the carriage is moved, and the ink is supplied from an ink tank at a fixed position through the ink supply tube.
In this method, since the ink is supplied through the flexible ink supply tube, a locus of movement of the ink supply tube is not defined and a large movement space is required. This is a barrier to a compact apparatus.
In another proposed method, a flexible tube is not used to supply the ink. Instead, an ink supply path to supply ink to a first ink tank mounted on the carriage and movable with the record element from a second ink tank located at a fixed position, is temporarily established when the carriage is at a predetermined position, and the ink is supplied through the ink supply path.
FIG. 1 is a sectional view of an ink jet printer which supplies the ink in the manner described above. Numeral 1 denotes an ink jet head mounted on a carriage 3 which is movable along a slide shaft 2, numeral 4 denotes a supply tube for supplying ink from a first tank 5 in the carriage 3 to the ink jet head 1, numeral 6 denotes a level sensor for detecting remainder of the ink in the first tank 5, and numeral 7 denotes an opening formed on a side of the first tank 5 for forming a supply path. FIG. 1 shows a state in which the carriage 3 is at a home position and the ink supply path from a second tank (not shown) to the first tank 5 is established. A needle pipe 8 is inserted into the first tank 5 through the opening 7. Numeral 9 denotes a flange which limits the amount of insertion of the needle pipe 8, numeral 10 denotes a compression spring which limits the insertion force of the needle pipe 8, and numeral 11 denotes a supply tube for connecting the needle pipe 8 with the second tank (not shown). Numeral 12 denotes a carriage which supports the needle pipe 8 to be axially movable. It is supported on a slide shaft 15 by a slide bearing 16 and a bearing housing 17 and driven left and right by a pinion gear 14 coupled to a motor (not shown) and a rack 13.
When the level sensor 6 detects that the amount of ink remaining in the first tank 5 is small, the carriage 3 is moved along the slide shaft 2, stops at the home position, and the carriage 12 which has been standing by at a rightward position is moved in a direction of the arrow so that the needle pipe 8 is inserted into the opening 7 formed in the first tank 5 on the carriage 3 to establish the ink supply path.
In order to establish the supply path in this method, the center of the opening 7 and the center of the needle pipe 8 must be aligned. In the apparatus shown in FIG. 1, the needle pipe 8 can be relatively easily inserted into the opening 7 because a diameter of the opening 7 is much larger than a diameter of the needle pipe 8.
On the other hand, in an ink jet printer, as the viscosity of ink at the leading end of the nozzle increases, the ink is not discharged. This problem may be resolved by applying a high pressure to the ink behind the nozzle to eject the high viscosity ink at the leading end of the nozzle. However, since air readily leaks from a clearance between the needle pipe 8 and the opening 7, the high pressure cannot be applied to the ink in this arrangement. In order to allow the application of high pressure to the ink in the arrangement of FIG. 1, a sealing member such as an O-ring may be used in the opening 7. However, if the O-ring is mounted in the opening 7, the center of the O-ring and the center of the needle pipe 8 must be aligned with a much higher accuracy than that required in FIG. 1, because even a slight misalignment will lead to a large increase of the insertion force since the needle pipe 8 shown in FIG. 1 is supported with a freedom of only axial direction.
In FIG. 1, one pair of opening and needle pipe are used. In a color ink jet printer, at least four pairs (and eight pairs if ink circulation is required) of supply path establishing means are necessary (to supply yellow, magenta, cyan and black inks to heads). Therefore, very high precision for the positions of the opening and arrangement of the needle pipes is required. Because centering errors of the respective supply path establishing means are not exactly zero, the supply path establishing means interfere with each other when the needle pipes are inserted, and a very large insertion force is required. Thus, in order to develop a very large moment on the slide shaft along which the carriage slides and apply a large radial load to the slide bearing and to attain high precision and assure durability, the diameter of the slide shaft must be unreasonably increased.
On the other hand, in an ink jet printer which records data by ink, the leading end of the nozzle of the record element or orifice is clogged due to the increase of viscosity of the ink at a low temperature, or by evaporation of water at a high temperature. Thus, high pressure is applied to the ink in the supply path to eject the high viscosity ink at the leading end of the nozzle or the orifice to restore the print function of the record element.
However, in the method in which the ink supply path is temporarily established to supply the ink, the ink leaks from the temporarily established ink supply path when the high pressure is applied to the ink in the supply path. As a result, it is not possible to eject the high viscosity ink in the record element by applying high pressure to the ink.
In the method of supplying the ink through the temporary supply path, dust may be deposited on the supply path establishing means while the supply path is not established such as when the carriage is moved to print data. The dust may go into the supply path when the supply path is temporarily established and block the leading end of the nozzle. This leads to non-discharge of the ink droplet.